MODELING THE EFFECT OF MICROSTRUCTURE ON FOOD EXTRACTION

Several cases of extraction of food components were analyzed applying the diffusion theory and Fick's second law to different microstructural architectures. A mathematical algorithm was developed for a two-dimensional heterogeneous system and programmed in MATLAB. Architectures examined include: (1) structure with straight pores, (2) flake with impermeable platelets, (3) matrix with impermeable dispersed particles and, (4) cellular material. Results show that the architecture of phases in the solid matrix is more important than parameters normally used to correct the diffusivity for structural effects (tortuosity, porosity, volume fraction, etc.). Simulated extraction curves were similar to those obtained from experimental data where an empirical effective diffusivity was calculated. These results suggest a more fundamental approach to modeling of extraction in foodstuffs based on the microstructure and local architecture. Le procede d'extraction solide-liquide de composants alimentaires peut etre modelise en appliquant la theorie de la diffusion et la deuxieme loi de Fick. Differents cas sont analyses avec ces modeles en tenant compte de la microstructure de l'aliment. L'architecture de la matrice solide (presence de pores droits, de couches impermeables, de particules dispersees, ou d'une matrice cellulair) est plus importante que les parametres de structures (porosite, tortuosite, ....).